Wiring parralel direct and regulated - possible?

[ekubec]

Hey folks,

New member with following systems :

-3KW grid tied PV system
-30 tube evacuated tube water heating system

-zone from above water system heating garden bed
-zone from above water system heating greenhouse

- 60 watt panel running water pump and fan in greenhouse (with deep cycle battery)

My question has to do with the last bit. When I run the water pump and fan direct from the 60 watt panel, they of course spin faster as the voltage is higher. When I hook up the battery, of course they run slower.

My question is:

Can I, maybe using diodes, run a circuit that charges the battery during the day, powers fan and pump direct spinning fast) and runs the circuit on battery at night?

The 'why' is: the solar heat gain is intense during the day. The pump pumps water from 175 gallons of water in a couple of bags through a Radiator that is attached to the fan. The faster the spin, the more Btu s of heat I can move from the air into the water. At night, the heat loss is gradual, so slower spin is okay

[ekubec]

Forgot to mention that the charging circuit of course includes a solar charge regulator.

[Mike90250]

Welcome. From past experience, I can say the 60w panel won't go far supplying fan, pump and battery charge. beware of over-voltaging the fan and pump when powering directly off an 18V panel, which is nominal 12V battery charge source. Steering Diodes won't solve the issue easily.

[ekubec]

I ran an 'amp meter' (can't recall the real name which indicates my level of expertise) for the water pump, the fan and the WILLHI temperature controller (both relay on and relay off) and here is what I got for amperage.

Conditions: PV direct (no controller or battery) and voltage 22 volts (again 60 watt panel):

Fan: 1.2 amps (start up about 1.35)
Water pump: .3 amps (start up about .45)
WillHi 50 ma / 70 ma (relay open / relay closed)

I have not run the test with the battery and controller (12 volts instead).

So, full sun PV direct: 60 watts = 22 volts X 2.7 amps. Draw at 22 volts (lets round up) = 1.6 amps. 2.7 amps - 1.6 amps = 1.1 spare amps or 40% spare capacity (ideal)

Not sure of the math on the following, but if I am running it all through the charge controller on a '12 volt' (actual 13 volts during charge) battery: 60 watts = 13 volts X 4.61 amps.

What would I expect the draw to be from the components?

would it be proportional (eg., amperage goes up in each case)?

The motors don't spin as fast, so it must not be generating the same amount of power (watts). So I have to think that I would have at least 40% spare capacity in the 12 volt controlled circuit.

-e

[bcroe]

Hey folks,

New member with following systems :

-3KW grid tied PV system
-30 tube evacuated tube water heating system

-zone from above water system heating garden bed
-zone from above water system heating greenhouse

- 60 watt panel running water pump and fan in greenhouse (with deep cycle battery)

My question has to do with the last bit. When I run the water pump and fan direct from the 60 watt panel, they of course spin faster as the voltage is higher. When I hook up the battery, of course they run slower.
My question is
Can I, maybe using diodes, run a circuit that charges the battery during the day, powers fan and pump direct spinning fast) and runs the circuit on battery at night?

The 'why' is: the solar heat gain is intense during the day. The pump pumps water from 175 gallons of water in a couple of bags through a Radiator that is attached to the fan. The faster the spin, the more Btu s of heat I can move from the air into the water. At night, the heat loss is gradual, so slower spin is okay

If you are already grid tied at the 3 KW level, why not just connect a 12VDC power supply to the line,
and use temp or timers to run fans & pumps? Building up another adequate battery based system will add
considerable cost & maintenance issues to your system. Bruce Roe